This invention relates in general to molding apparatus and deals more particularly with an improved ejector retraction mechanism for positively controlling the retraction of an ejector mechanism in a molding apparatus.
In an apparatus for the manufacture of molded products, and utilizing molding dies an ejector mechanism is usually provided to assure positive removal of finished workpieces from the dies during the die opening cycle. Such ejector mechanisms usually employ one or more ejector pins movable into a die cavity section associated with one of the molding dies during the die opening cycle. An ejector retraction mechanism operates to retract the ejector pins from the mold cavity section during the die closing cycle and before the dies are fully closed to prevent damage to the ejector pins or the molding cavity. More sophisticated molding apparatus for the production of hollow molded products usually requires one or more core elements arranged to move with and relative to one of the mold cavity plates to move into and out of the mold cavity defined by the plates during the operational cycle of the apparatus. More specifically, the core element or elements are generally arranged to move into molding position during the mold closing cycle and to retract during the opening cycle. An ejector retraction mechanism for such molding apparatus must operate in properly timed relation with the cycle of the molding dies to permit the ejector mechanism to operate during the opening cycle and to assure positive retraction of the ejector mechanism during the closing cycle to prevent risk of damage to either the ejector mechanism or the core element or elements which may move in the path of travel of the ejector mechanism. The aforedescribed problem is discussed in some detail in U.S. Pat. No. 3,516,302 to Muttart, issued June 23, 1970. The present invention is concerned with improved ejector retraction mechanism of the aforedescribed type. It is the general aim of the present invention to provide an improved ejector retraction mechanism of simple durable construction for low cost manufacture and simple installation and which may be installed on a molding apparatus or mold base therefor without reducing the effective usable area of the molding die cavity plates.